Velayati was responding Sunday to U.S. Secretary of State John Kerry. Kerry said President Barack Obama was "fully ready" to pull the U.S. out before agreeing to a deal leaving Tehran with potent nuclear arms-making ability.

Their exchange may be an attempt to play to their home audiences but could also signal difficulties at the talks with only a month to go to a late-March deadline for a first-stage deal.

Iran says it does not want such weapons but is negotiating in hopes of sanctions relief.